1
2/*
3 * Copyright 2014 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#ifndef GrResourceKey_DEFINED
10#define GrResourceKey_DEFINED
11
12#include "GrTypes.h"
13#include "GrBinHashKey.h"
14
15class GrResourceKey {
16public:
17    static GrCacheID::Domain ScratchDomain() {
18        static const GrCacheID::Domain gDomain = GrCacheID::GenerateDomain();
19        return gDomain;
20    }
21
22    /** Uniquely identifies the GrGpuResource subclass in the key to avoid collisions
23        across resource types. */
24    typedef uint8_t ResourceType;
25
26    /** Flags set by the GrGpuResource subclass. */
27    typedef uint8_t ResourceFlags;
28
29    /** Generate a unique ResourceType */
30    static ResourceType GenerateResourceType();
31
32    /** Creates a key for resource */
33    GrResourceKey(const GrCacheID& id, ResourceType type, ResourceFlags flags) {
34        this->init(id.getDomain(), id.getKey(), type, flags);
35    };
36
37    GrResourceKey(const GrResourceKey& src) { fKey = src.fKey; }
38
39    GrResourceKey() { fKey.reset(); }
40
41    void reset(const GrCacheID& id, ResourceType type, ResourceFlags flags) {
42        this->init(id.getDomain(), id.getKey(), type, flags);
43    }
44
45    uint32_t getHash() const { return fKey.getHash(); }
46
47    bool isScratch() const {
48        return ScratchDomain() ==
49            *reinterpret_cast<const GrCacheID::Domain*>(fKey.getData() +
50                                                        kCacheIDDomainOffset);
51    }
52
53    ResourceType getResourceType() const {
54        return *reinterpret_cast<const ResourceType*>(fKey.getData() +
55                                                      kResourceTypeOffset);
56    }
57
58    ResourceFlags getResourceFlags() const {
59        return *reinterpret_cast<const ResourceFlags*>(fKey.getData() +
60                                                       kResourceFlagsOffset);
61    }
62
63    bool operator==(const GrResourceKey& other) const { return fKey == other.fKey; }
64
65    // A key indicating that the resource is not usable as a scratch resource.
66    static GrResourceKey& NullScratchKey() {
67        static const GrCacheID::Key kBogusKey = { { {0} } };
68        static GrCacheID kBogusID(ScratchDomain(), kBogusKey);
69        static GrResourceKey kNullScratchKey(kBogusID, NoneResourceType(), 0);
70        return kNullScratchKey;
71    }
72
73    bool isNullScratch() const {
74        return this->isScratch() && NoneResourceType() == this->getResourceType();
75    }
76
77private:
78    enum {
79        kCacheIDKeyOffset = 0,
80        kCacheIDDomainOffset = kCacheIDKeyOffset + sizeof(GrCacheID::Key),
81        kResourceTypeOffset = kCacheIDDomainOffset + sizeof(GrCacheID::Domain),
82        kResourceFlagsOffset = kResourceTypeOffset + sizeof(ResourceType),
83        kPadOffset = kResourceFlagsOffset + sizeof(ResourceFlags),
84        kKeySize = SkAlign4(kPadOffset),
85        kPadSize = kKeySize - kPadOffset
86    };
87
88    static ResourceType NoneResourceType() {
89        static const ResourceType gNoneResourceType = GenerateResourceType();
90        return gNoneResourceType;
91    }
92
93    void init(const GrCacheID::Domain domain,
94              const GrCacheID::Key& key,
95              ResourceType type,
96              ResourceFlags flags) {
97        union {
98            uint8_t  fKey8[kKeySize];
99            uint32_t fKey32[kKeySize / 4];
100        } keyData;
101
102        uint8_t* k = keyData.fKey8;
103        memcpy(k + kCacheIDKeyOffset, key.fData8, sizeof(GrCacheID::Key));
104        memcpy(k + kCacheIDDomainOffset, &domain, sizeof(GrCacheID::Domain));
105        memcpy(k + kResourceTypeOffset, &type, sizeof(ResourceType));
106        memcpy(k + kResourceFlagsOffset, &flags, sizeof(ResourceFlags));
107        memset(k + kPadOffset, 0, kPadSize);
108        fKey.setKeyData(keyData.fKey32);
109    }
110    GrBinHashKey<kKeySize> fKey;
111};
112
113#endif
114